Seriously...I don't want to be rude but you need to return that RTC to the fish store if they will take it back and start with some corys or mabye syn. cats which you can actually provide a home for and keep in your tank for life (or close to it).
Its really obvious your a beginner and a young kid and I certainly don't want to discourage you from getting into this hobby, but you really need to start with beginner fish and do a lot more research before you attempt to keep a large catfish.
We've all gone through this phase, so don't feel bad...when I was starting in the hobby I tried to stuff a silver aro in a 55. But c'mon man be honest with yourself...you are completely and totally unprepared to care for this animal. Start with some easier fish my friend.